Communication system and method over local area network wiring

ABSTRACT

A device for enabling a local area network wiring structure to simultaneously carry digital data and analog telephone signals on the same transmission medium. It is particularly applicable to a network in star topology, in which remote data units (e.g. personal computers) are each connected to a hub through a cable comprising at least two pairs of conductors, providing a data communication path in each direction. Modules at each end of the cable provide a phantom path for telephony (voice band), signals between a telephone near the data set and a PBX, through both conductor pairs in a phantom circuit arrangement. All such communication paths function simultaneously and without mutual interference. The modules comprise simple and inexpensive passive circuit components.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 12/333,617, filed onDec. 12, 2008, which is a continuation of U.S. application Ser. No.11/125,200, filed on May 10, 2005, now U.S. Pat. No. 7,480,233, issuedon Jan. 20, 2009, which is continuation of U.S. application Ser. No.09/666,856, filed on Sep. 21, 2000, now U.S. Pat. No. 6,961,303, issuedon Nov. 1, 2005

FIELD OF THE INVENTION

The present invention relates to the field of common networks for datacommunication and telephony, and, more specifically, to the networkingof telephone sets within a building over digitally oriented local areanetwork wiring, simultaneously with the data transmission.

BACKGROUND OF THE INVENTION

Small office and business environments commonly employ a multiplicity ofwork cells, each equipped with a telephone set and a computer. Twoseparate networks are usually employed for communication among the cellsand between them and the outside world—a telephone network, connectingbetween the telephone sets and outside telephone lines, and a so-calledlocal area network (LAN), connecting the computers among themselves andto outside network lines.

The term computer or personal computer will be understood to include aworkstation or other data terminal equipment (DTE) or at least onedigital device capable of inputting and outputting data, whereby eachcomputer includes an interface for connection to a local area network(LAN), used for digital data transmission; any such device will also bereferred to as a remote digital device. The term telephone set will beunderstood to include any device which can connect to a PSTN (PublicSwitched Telephone Network), using telephony band signals, such as faxmachine, automatic answering machine or dial-up modem; any such devicewill also be referred to as a remote- or local telephone device.

Such an environment is depicted in FIGS. 1 a and 1 b, which show atypical small office/business configuration, requiring two separate andindependent networks. FIG. 1 a shows a telephony network 10 comprising aPABX (Private Automatic Branch Exchange) 11, connected via lines 12 a,12 b, 12 c and 12 d to telephone devices 13 a, 13 b, 13 c and 13 drespectively. The telephone are of the POTS (Plain Old TelephoneService) type, requiring each of the connecting lines 12 to consist of asingle pair of wires.

FIG. 1 b shows a local area network (LAN) 15 for allowing communicationbetween computers. Such a network comprises a hub (or switching hub) 16,connected via lines 17 a, 17 b, 17 c and 17 d to computers 18 a, 18 b,18 c and 18 d respectively. Popular types of LANs are based on theIEEE802.3 Ethernet standard, using 10BaseT or 100BaseTX interfaces andemploying, for each connecting line 17, two twisted pairs of wires—onepair for transmitting and one pair for receiving.

Installation and maintenance of two separate networks is complicated andexpensive. It would therefore be advantageous, especially in newinstallations, to have a combined wiring network system that serves bothtelephony and data communication requirements.

One approach is to provide a LAN only, which serves for normalinter-computer communication, and make it serve also for telephony. Onegeneral method for this approach, in common usage today, utilizesso-called Voice-Over-Internet-Protocol (VoIP) techniques. By suchtechniques, known in the art, telephone signals are digitized andcarried as data in any existing LAN. Systems employing such techniquesare, however, complex and expensive, and the quality of the voicecarried by currently available technology is low.

Another, opposite approach is to utilize an existing telephoneinfrastructure for simultaneously serving as both telephone and datanetworking. In this way, the task of establishing a new local areanetwork in a home or other building is simplified, because there are noadditional wires to install.

U.S. Pat. No. 4,766,402 to Crane teaches a way to form a LAN overtwo-wire telephone lines, but without the telephone service.

The concept of frequency division multiplexing (FDM) is well-known inthe art, and provides a means of splitting the inherent bandwidth of awire into a low-frequency band, capable of carrying an analog telephonysignal, and a high-frequency band, capable of carrying data or othersignals. Such a technique, sometimes referred to as ‘data over voice’,is described, for example, in U.S. Pat. Nos. 5,896,443, 4,807,225,5,960,066, 4,672,605, 5,930,340, 5,025,443 and 4,924,492. It is alsowidely used in xDSL systems, primarily Asymmetric Digital SubscriberLoop (ADSL) systems.

A typical system employing FDM is illustrated in FIG. 2, which showsschematically a combined telephony/data network 20, providing in thiscase connections to two work cells by means of corresponding two cables12 a and 12 b, each comprising a single twisted pair of wires. The lowerpart of the spectrum of cable 12 a is isolated by Low Pass Filters (LPF)22 a and 22 b, each connected to a respective end of the cable.Similarly, the higher part of the spectrum is isolated by respectiveHigh Pass Filters (HPF) 21 a and 21 b. The telephony network uses thelower spectrum part by connecting the telephone 13 a and the PABX 11 tothe respective LPFs. In order to use the higher part of the spectrum fordata communication, telephone-line modems 23 a and 23 b are respectivelyconnected to the HPFs 21 a and 21 b at both cable ends. Hub 16 connectsto modem 23 a, while, on the user side, modem 23 b connects to computer18 a, thus offering connectivity between the computer and the hub. Thespectrum of the other cable 12 b is similarly split and cable 12 bconnects telephone set 13 b to PABX 11 via LPFs 22 c and 22 d, whilecomputer 18 b connects to hub 16 via modem 23 d, coupled to HPF 21 d,and modem 23 c, coupled to HPF 21 c. Additional telephones 13 andcomputers 18 can be added in the same manner. This prior-art concept isdisclosed in U.S. Pat. No. 4,785,448 to Reichert et al. (hereinafterreferred to as “Reichert”) and U.S. Pat. No. 5,841,841 to Dodds et al.(hereinafter referred to as “Dodds”). Both Reichert and Dodds suggest amethod and apparatus for applying frequency domain/division multiplexing(FDM) technique for residential telephone wiring, enablingsimultaneously carrying telephone and data communication signals, asdescribed above.

Network 20, employing an FDM method, typically requires two modems (suchas 23 a and 23 b in FIG. 2) for each connected cell. Such modems arecomplex and expensive. In addition, the low communication quality of atypical telephone line, which was designed to carry low-frequency(telephony) signals only, limits both the data-rate and the distance ofthe data communication.

The concept of forming a phantom channel to serve as an additional pathin a two wire-pairs communication system is known in the art oftelephony, and disclosed in several patents, classified under U.S. Class370/200. Commonly, such a phantom channel path is used to carry power tofeed remote equipment or intermediate repeaters. In some prior-artsystems, exemplified by U.S. Pat. Nos. 4,173,714, 3,975,594, 3,806,814,6,026,078 and 4,937,811, the phantom channel is used to carry additionalsignals, such as metering and other auxiliary signals. Thus, all suchsystems use the phantom channel only as means for helping thecommunication service over the main channels. None of the mentionedprior-art uses the phantom channel for carrying an additionalcommunication type of service, or for functionally combining twodistinct networks.

It would thus be desirable to allow a data networking system tosimultaneously also provide telephone service without any additionalwiring.

SUMMARY OF THE INVENTION

It is an object of the invention to allow a data networking system tosimultaneously also provide telephone service without any additionalwiring.

This object is realized in accordance with a broad aspect of theinvention by a communication network for providing simultaneous digitaldata- and analog telephone communication between a central location andat least one remote location, the communication network comprising: acentral digital device, a central telephone device and, for each remotelocation—a remote digital device, a remote telephone device and a cablehaving a remote end at the respective remote location and a near end atthe central location; said cable including at least two pairs ofconductors, each pair operative as a data channel for carrying datasignals between said remote digital device and said central digitaldevice and said at least two pairs cooperatively forming a phantomchannel, operative to carry telephone signals between said remotetelephone device and said central telephone device.

Conventional data networks use a four-conductor circuit arrangementproviding two communication channels between two units. For example, ina local area network based on Ethernet 10BaseT or 100BaseTX, two pairsof conductors are employed between a hub and DTE such as a computer. Bymeans of the invention, POTS connection, such as between exchange andtelephone apparatus, is accomplished simultaneously over the same fourconductors used for the two communication channels without interference.The POTS service communication is accomplished via a phantom circuitarrangement over the four conductors.

Such configuration can be employed within small office or smallbusiness, wherein single wiring infrastructure is used for distributingboth data and telephone signals from a central location, including a huband an exchange to a remote station, each such station comprising atelephone unit and a data unit (e.g. desktop computer).

The present invention also provides a circuit arrangement wherein acable that includes two twisted-conductor pairs provides both a two-waydata communication channel for a connected computer and, simultaneously,a path for POTS signal to and from a connected telephone set, using thephantom channel method. In the preferred embodiment, the datacommunication channel consists of an Ethernet IEEE802.3 LAN channel and10BaseT, or 100BaseTX, interfaces.

According to the invention, each two-conductor pair is terminated ateach of its ends with a center tapped primary transformer winding(hereinafter cable-side winding), whereby each conductor of the pair isconnected to a respective end of the cable side winding. Each winding isinductively coupled to a secondary winding (hereinafter referred to asequipment side winding), whose ends are connected to another pair ofconductors that form the continuation channel for the data carryingsignal, wherein the equipment side winding is connected to the datacommunication equipment. The center taps of each of the two primarywinding at any end of the cable are connectable to the respectiveconductors of a telephone circuit, to carry the POTS signals. Thus, thetwo pairs of conductors at opposite ends of the cable, through thecenter taps of the respective primary transformer windings, form firstand second connections of the two conductor phantom channel, which isused for carrying the telephone signal.

The invention can be implemented by means of two modules—one at each endof the two-conductor-pairs cable. Each module comprises twotransformers, with a center-tap in the primary (cable side) winding. Themodule retains the two-pair data communication capability, whilesimultaneously including a phantom channel via the center-tapconnections, for telephone service. The phantom channel can be accessedvia a connector in the module. The module can be a stand-alone unit, orintegrated within any unit in the network, such as a digital networkhub, a telephone exchange, a server computer or telephone set.Alternatively, the module can be integrated within a wall outletconnected to one or both ends of the cable.

In another embodiment, the modules form a kit, which is used to upgradean existing local area network to support telephone networking also.

The invention can be used in a small office or small businessenvironment, which has a central location that comprises a telephoneexchange and a digital network concentration unit (such as a hub, aswitch or a router), connected to multiple remote work stations via LANwiring.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carriedout in practice, a preferred embodiment will now be described, by way ofnon-limiting example only, with reference to the accompanying drawings,in which:

FIGS. 1 a and 1 b show respectively a common prior art telephone andLocal Area Network configuration as used within a small office or asmall business;

FIG. 2 shows a prior art telephone and local area networks using thetelephone-wiring infrastructure;

FIG. 3 shows a combined telephone and data communication networkaccording to the present invention;

FIG. 4 shows schematically a data communications network having multiplephantom channels according to the present invention all sharing a commonreturn;

FIG. 5 a shows schematically a computer modified according to theinvention for direct coupling to a telephone set;

FIG. 5 b shows schematically a telephone set modified according to theinvention for direct coupling to a computer;

FIG. 6 shows modified wall outlet that adds a phantom channel telephoneservice to an existing data communication system according to thepresent invention; and

FIGS. 7 a to 7 d show different views of an attachable wall plugconnector that adds a phantom channel telephone service to an existingdata communication system according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description it is to be noted that the drawings anddescriptions are conceptual only. In actual practice, a single componentcan implement one or more functions; alternatively, each function can beimplemented by a plurality of components and circuits. In the drawingsand descriptions, identical reference numerals are use to indicate thosecomponents that are common to different embodiments or configurations.

FIG. 3 illustrates a preferred embodiment of the present invention. Thenetwork 30 is a part of an IEEE802.3 local area network, using 10BaseTinterfaces. A hub 16, defining a central location, is connected to atypical computer 18 a via a cable that includes two wire pairs 17 a 1and 17 a 2. Each pair is operative to carry data in one direction only,one pair, say 17 a 1, carrying data from the hub 16 to the computer 18a, while the other pair, 17 a 2, carries data in the other direction.FIG. 3 also shows a telephone set 13 a, associated with computer 18 aand preferably near it, and a telephone private automatic branchexchange (PABX) 11, which is preferably also at the central location.The term hub is used herein to represent any digital networkconcentrating unit and may equally refer to a switching hub, a router, aserver computer or to any digital device having multiple data ports; anyof these being also referred to herein as a central digital device.Similarly, PABX is used herein to represent any type of centraltelephone switching unit and will also be referred to as a centraltelephone device.

According to the invention, a signal transformer is inserted at each endof each wire pair, whereby, for example, transformer 31 a 1 is insertedat the end of wire pair 17 a 1 that is near hub 16 and transformer 31 b1 is inserted at the end of wire pair 17 a 1 that is near computer 18 a.Similarly, transformers 31 a 2 and 31 b 2 are inserted at the ends ofwire pair 17 a 2 that are near hub 16 and computer 18 a, respectively.The signal transformers bearing the prefix 31 are designed so that thesignal attenuation via these transformers is negligible. Hence, theperformance of the data communication network is fully retained, and thehub 16 continues to communicate fully with the computer 18 a in theusual manner. Such transformers are known in the art and are often usedin LANs, in order to meet isolation and common-mode rejectionrequirements. Commonly, such signal transformers are equipped with aprimary winding and a secondary winding both being untapped coils. Inthe invention, each signal transformer bearing the prefix 31, say 31 a 2has a primary winding 35, whose ends are connected to the respectivewires of the cable, and a secondary winding 36, whose ends are connectedto the respective system component (hub 16 or computer 18 a).

However, unlike the conventional configuration for signal transformers,according to the present invention each primary winding 35 has acenter-tap shown as 37 a 1 and 37 a 2, for the two signal transformers31 a 1 and 31 a 2, respectively. PABX 11 is connected, via tworespective wires 38 a, to the center-taps 37 a 1 and 37 a 2 oftransformers 31 a 1 and 31 a 2. Similarly, the telephone set 13 a isconnected, via two respective wires 38 b, to the center-taps 37 b 1 and37 b 2 of transformers 31 b 1 and 31 b 2, respectively. In thisconfiguration, the telephony signals are carried in a ‘phantom’ waytogether with the data communication signals, without any interferencebetween the two. In practice, the hub side transformers 31 a 1 and 31 a2 may be integrated to form a module 32 a, while the computer sidetransformers 31 b 1 and 31 b 2 may be integrated to form a module 32 b.While the network 30 has so far been described as supporting a singlecomputer and a single telephone, additional work cells, each comprisinga telephone and a computer can be supported, whereby each computer isconnected with hub 16 through a corresponding two wire pairs cable, byinserting an additional set of modules 32 a and 32 b in each such cable.

While the invention has been described specifically for 10BaseT (10Mb/s) interfaces, the invention can be equally applied to 100BaseTX (100Mb/s) interfaces. Furthermore, the invention can be equally applied inany wired networking system using at least two wire pairs. Transformerscan be used in all wired communication systems whose signals do notinclude direct current (DC) components. In systems that use four or morepairs of wires, such as those based on the evolving 1000BaseTX Ethernetstandard, each two pairs can be used to form a single phantom channel.Thus, four pairs can form two phantom channels, each carrying one POTScircuit, by terminating each pair with a transformer as described above.Alternatively and preferably, as shown in FIG. 4, three pairs 17 a 1, 17a 2 and 17 a 3 can each form a phantom channel with the fourth pair 17 a4, which serves as the common return path. In this case, each telephonecircuit 13 a, 13 b and 13 c has one of its two wires connected to thecenter-tap 37 b 1, 37 b 2 and 37 b 3 of the respective transformer 31 b1, 31 b 2 and 31 b 3 at the corresponding end of the respective pair andthe other wire—to the center-tap 37 b 4 of the transformer 31 b 4 at thecorresponding end of the common pair. More generally, with N pairs ofconductors, each pair serving as a data channel, it is possible tosimilarly provide N−1 phantom channels for telephone service.

In the configuration shown in FIG. 3 the modules 32 a and 32 b arestand-alone modules, mechanically separate from other components in thenetwork. However, also other configurations are possible. For example,the hub side module 32 a can be integrated, fully or in part, within thehub 16. In such a case, the hub's existing data connection-unit (such asa distribution frame—for connecting thereto all line pairs) ispreferably substituted by one that includes module 32 a; in addition, atelephone connector is provided, for connecting all telephone lines(whose other ends are connected to their respective center taps inmodule 32 a) to the PABX. Alternatively, module 32 a can be similarlyintegrated within PABX 11, whereby an appropriate connection with thehub is provided.

FIG. 5 a shows schematically an arrangement where the computer sidemodule 32 b is integrated, fully or in part, within the computer 18 a.Thus, the secondary windings 36 of the transformers 31 a 1 and 31 a 2are connected to receiver and transmitter circuitry 39 a and 39 b withinthe computer 18 a. The ends of the primary windings 35 of thetransformers 31 a 1 and 31 a 2 are connected to a standard socket outlet40 for connecting to the network. The center-taps 37 a 1 and 37 a 2 areconnected to a standard telephone outlet 41, enabling connection theretoof a telephone set such as designated 13 a in FIG. 3.

FIG. 5 b shows schematically the complementary arrangement where themodule 32 b is integrated the telephone set 13 a. Thus, the secondarywindings 36 of the transformers 31 a 1 and 31 a 2 are connected to astandard outlet 42 for connecting thereto a computer such as designated18 a in FIG. 3. The ends of the primary windings 35 of the transformers31 a 1 and 31 a 2 are connected to a standard socket outlet 43 forconnecting to the network. The center-taps 37 a 1 and 37 a 2 areconnected to telephone circuitry 44, within the telephone set 13 a.

Alternatively, the computer side module 32 b can be integrated within awall connector allowing direct or indirect connection to an existingwall socket outlet. Thus, such a wall connector can be constituted by asubstitute wall socket having integrated therein a pair of signaltransformers and two female outlets for connecting a computer andtelephone thereto, respectively. Alternatively, the wall connector canbe constituted by a plug connector having integrated therein a pair ofsignal transformers and two female outlets for connecting a computer andtelephone thereto, respectively. Such a plug connector allows a computerand telephone to be connected to an existing wall socket outlet withoutrequiring any modification thereto.

FIG. 6 shows the faceplate of a modified socket outlet 45 according tothe invention. Two conductor pairs are connected to the outlet at therear (not shown in the Figure), connected to the primary windings of twosignals transformers housed in it (not shown in the Figure). Thesecondary windings of the transformers are connected to RJ-45 dataconnector 46, while the center taps are connected to the RJ-11 telephonyconnector 47. Such an outlet is physically similar in size, shape, andoverall appearance to a standard outlet, so that such an outlet can besubstituted for a standard outlet in the building wall. No changes arerequired in the overall LAN line layout or configuration. Such an outletcan easily substitute an existing standard data outlet to thusadditionally provide telephony support. Thus a conventional outlet has asingle female connector having two pairs of wiper contacts connected tothe respective twisted-wire pairs for data transmission and reception. Acomputer is plugged into such a conventional outlet via a single maleconnector (plug) having four pins: two for handling data transmissionand two for handling data reception. On inserting the plug into thesocket outlets, the pins brush against the wiper contacts in the socketoutlet, thus establishing electrical connection between the two.

The invention allows for the conventional outlet to be replaced by amodified outlet having therein a pair of signal transformers, the endsof whose respective primary windings are adapted to be connected to theends of a respective conductor pair in the network. The secondarywinding of each signal transformer is connected internally to arespective pair of wiper contacts of a first female connector. Thus, theends of both secondary windings are connected to first female connectorby means of four wiper contacts in total. The respective center-taps ofeach of the two primary windings are connected to a pair of wipercontacts in a second female connector proximate the first femaleconnector. Thus, a computer can be connected, via four pins of asuitable jack plug, to the first female connector, while a telephone canbe connected, via two pins of a suitable jack plug to the second femaleconnector. The two wire pairs 17 a 1 and 17 a 2 are routed and connectedto such an outlet, which will now comprise two faceplate connectors—adata connector (e.g. RJ-45 for 10BaseT) and a telephone connector (e.g.RJ-11).

Such an implementation requires that the socket outlets in an existingdata network be replaced by a modified outlet according to theinvention. FIGS. 7 a to 7 d show various views of a plug assembly 50according to the invention for operation in 10BaseT or 100BaseTXenvironment that allows the invention to be implemented withoutrequiring any modification to the data network or to the existing socketoutlet. In use, the plug assembly 50 is plugged into a standard socketoutlet and is retained therein by means of a latch 51. The plug assembly50 contains the module 32 b connected to separate data- and telephonysocket outlets 52 and 53 in a similar manner to the modified socketoutlet 45 described above with reference to FIG. 6. A standard RJ45 jackplug 54 is connected to the module 32 b for mating with the wall outletwhen plugged into its socket. The jack plug 54 thus includes two pairsof pins each connected to the primary winding of a respective signaltransformer within the module 32 b. The secondary windings of the twosignal transformers are connected to respective wiper contacts in thedata-telephony socket outlet 52. The respective center-taps of each ofthe primary windings are connected to a pair of wiper contacts in thetelephony socket outlet 53 proximate the data-telephony socket outlet52. Cables from the computer and the telephone set terminate in standardjack plugs that are plugged into the respective data- and telephonysocket outlets 52 and 53 within the plug assembly 50. Thus, the plugassembly 50 obviates the need for any changes to be made to the existinginfrastructure.

As mentioned above, 10BaseT and 100BaseTX interfaces, as well as otherdata communication interfaces, often include signal transformers in theline connection circuitry, in order to meet isolation and common-moderejection requirements. In such cases, additional transformers, thoughpossible, are not required and the method of the present invention canbe implemented by adding center-tap connections to the respectivewindings of the existing transformers and using them to form a phantomchannel, to serve for telephone connection in the manner describedabove. Alternatively, the existing transformers can be substituted byones with center-taps as specified above.

It is noted that, while a phantom channel has been known in the art, itsuse in the system and method disclosed herein is novel, because:

(a) Local area networks (LANs) in general, and Ethernet networks inparticular, currently do not employ phantom channels, nor is anyconfiguration employing such channels specified in the IEEE802.3standards; the concept is known in the realm of telephony only, which isvery different from that of data communication LANs.(b) Using a phantom channel itself to carry POTS service is not known inthe art; rather, phantom channels are used only to carry power to remoteunits and/or management- or control signals to support the main servicethat is provided by the two conductor pairs.

While the invention is described above relating to hub units, it isclear that any other multi-port data communication device can be used,such as switch, router or gateway.

The present invention also embraces a method for upgrading an existinglocal area network (LAN) installation that includes a two-conductor paircable between two digital devices, to also and simultaneously conveysignals between two telephone devices, the method comprising:

(a) inserting a first pair of signal transformers having center-tappedprimary windings at a first end of the cable, with respective ends ofthe primary windings connected to respective conductors of the cable;and

(b) inserting a second pair of signal transformers having center-tappedprimary windings at a second end of the cable, with respective ends ofthe primary windings connected to respective conductors of the cable;

thereby allowing respective secondary windings of each signaltransformer to be connected to the digital devices and allowing therespective center-taps of the signal transformers to be connected totelephone equipment.

If the LAN already includes signal transformers that do not havecenter-taps, they are, in step (a) above, replaced by the specifiedtransformers or, alternatively, a center-tap is added to each primarywinding.

While the invention has been described with respect to a limited numberof embodiments, it will be appreciated that many variations,modifications and other applications of the invention may be made.

What is claimed is:
 1. A device for a local area network (LAN), the LANincluding a LAN cable having at least four wire pairs to carry aplurality of data signals, and the device comprising: a firsttransformer having a primary winding and a secondary winding, the firsttransformer being operative to pass a first data signal; a secondtransformer having a primary winding and a secondary winding, the secondtransformer being operative to pass a second data signal; a thirdtransformer having a primary winding and a secondary winding, the thirdtransformer being operative to pass a third data signal; a fourthtransformer having a primary winding and a secondary winding, the fourthtransformer being operative to pass a fourth data signal, and theprimary winding of each one of the transformers being communicativelycoupled to a respective one of the four wire pairs, the secondarywinding of each one of the transformers being arranged within the devicefor transferring a respective one of the data signals to or from theassociated primary winding, and a first center-tap connection of theprimary winding of any one of the transformers to be paired with asecond center-tap connection of the primary winding of any other one ofthe transformers for providing a first phantom channel using the tworespectively associated pairs of the four wire pairs; circuitryconfigured to source a phantom signal over the phantom channel, thecircuitry coupled to the first center-tap connection and the secondcenter-tap connection; and a single enclosure housing the circuitry andalso housing the first, second, third and fourth transformers.
 2. Thedevice as claimed in claim 1 wherein the LAN and data communicationswithin the LAN are based on the IEEE802.3 Ethernet standard.
 3. Thedevice as claimed in claim 2 further comprising at least 1000 Mb/sinterfaces for communicative coupling to the at least four wire.
 4. Thedevice as claimed in claim 2 wherein the device is a multi-port datacommunication device.
 5. The device as claimed in claim 4 wherein themulti-port data communication device is a switch.
 6. The device asclaimed in claim 4 wherein the multi-port data communication device is arouter.
 7. The device as claimed in claim 4 wherein the multi-port datacommunication device is a gateway.
 8. The device as claimed in claim 1further comprising at least 1000 Mb/s interfaces for communicativecoupling to the at least four wire.
 9. The device as claimed in claim 1wherein the device is a multi-port data communication device.
 10. Thedevice as claimed in claim 9 wherein the multi-port data communicationdevice is a switch.
 11. The device as claimed in claim 9 wherein themulti-port data communication device is a router.
 12. The device asclaimed in claim 9 wherein the multi-port data communication device is agateway.
 13. The device as claimed in claim 1 wherein the device isconfigured to provide two simultaneous phantom channels using all of thefour wire pairs.
 14. The device as claimed in claim 1 wherein the atleast four wire pairs is N wire pairs, and the device is configured toprovide N−1 simultaneous phantom channels.
 15. The device as claimed inclaim 1 wherein the circuitry comprises telephone circuitry.
 16. Thedevice as claimed in claim 1 further comprising at least one femaleconnector coupled to the secondary windings of at least two of thefirst, second, third and fourth transformers.
 17. The device as claimedin claim 16 wherein the female connector is an RJ-45 data connector. 18.The device as claimed in claim 1 wherein the LAN further comprises adata unit couplable to the device, and the secondary windings of thefirst, second, third and fourth transformers provide four equipment sidewindings for the data unit.
 19. The device as claimed in claim 1 whereinthe phantom signal comprises power.
 20. The device as claimed in claim 1wherein the phantom signal comprises DC power.